Conversion to double from function_handle is not possible.

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Lakshay Sethi
Lakshay Sethi 2017-10-4
评论： Walter Roberson 2017-10-4
Cold someone help me with this. I'm trying to solve multiple ode s simultaneously. It says "Conversion to double from function_handle is not possible."
Here's the code
clc
clear all
[t,xa] = ode15s(@f,[0 80*3600],zeros(2499,1));
function dydt3 = f(t,x)
cpo=1e-7;
d=1.3;
p=5.7e-3;
dx=65/100;
dcdt=zeros(50,50);
for i=2:49
for j=2:49
dcdt(i,j)= @(x) (d*((x(i+1,j)+x(i-1,j)+x(i,j+1)+x(i,j-1)-4*x(i,j))/(dx^2)))
end
end
for j=2:49
dcdt(1,j)= @(x) (d*((x(1+1,j)+x(1+1,j)+x(1,j+1)+x(1,j-1)-4*x(1,j))/(dx^2)))
end
for i=2:49
dcdt(i,1)= @(x) (d*((x(i,1+1)+x(i,1+1)+x(i+1,1)+x(i-1,1)-4*x(i,i))/(dx^2)))
end
for j=2:49
dcdt(50,j)= @(x) (d*((x(50-1,j)+x(50-1,j)+x(50,j+1)+x(50,j-1)-4*x(50,j))/(dx^2)))
end
for i=2:49
dcdt(i,50)= @(x) (d*((x(i,50-1)+x(i,50-1)+x(i+1,50)+x(i-1,50)-4*x(i,50))/(dx^2)))
end
dcdt(50,1)=@(x) (d*((x(49,1)+x(49,1)+x(50,2)+x(50,2)- 4*x(50,1))/(dx^2)));
dcdt(50,50)=@(x) (d*((x(49,50)+x(49,50)+x(50,49)+x(50,49)-4*x(50,50))/(dx^2)));
dcdt(1,50)=@(x) (d*((x(1,49)+x(1,49)+x(2,50)+x(2,50)-4*x(1,50))/(dx^2)));
x(1,1)=@(x,t) ((d*x(1,2)+(dx*p*(cpo*((ap*exp(la.*t))+(1-ap)*exp(lb.*t)))))/(p*dx+d));
dcdt2= @(x,t) reshape(dcdt,[2500,1])
for i=1:2499
dcdt3(i)= dcdt2(i+1)
end
%dydt3 = dydt3';
end

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回答（1 个）

James Tursa
James Tursa 2017-10-4
编辑：James Tursa 2017-10-4
You can't store function handles inside a double variable. You must use a cell array instead. E.g.,
>> f = zeros(2,1);
>> f(1) = @(x)x^2
??? The following error occurred converting from function_handle to double:
Error using ==> double
Conversion to double from function_handle is not possible.
>> f = cell(2,1);
>> f{1} = @(x)x^2
f =
@(x)x^2
[]
>> f{2} = @(x)x^3
f =
@(x)x^2
@(x)x^3
>> f{1}(4)
ans =
16
>> f{2}(4)
ans =
64
That being said, it is not clear to me why you are trying to create an array of function handles.
  2 个评论
Lakshay Sethi
Lakshay Sethi 2017-10-4
Thanks again but I'm new to matlab and not very familiar with the jargon. Could you please elaborate your answer or tell me what's wrong with my code.
Walter Roberson
Walter Roberson 2017-10-4
Remove all of the @(x) and @(x,t). For example, rather than
dcdt(i,j)= @(x) (d*((x(i+1,j)+x(i-1,j)+x(i,j+1)+x(i,j-1)-4*x(i,j))/(dx^2)))
use
dcdt(i,j)= (d*((x(i+1,j)+x(i-1,j)+x(i,j+1)+x(i,j-1)-4*x(i,j))/(dx^2)));

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